A tractor or a tractor-like vehicle is capable of performing one of a variety of work tasks when one of a variety of work implements, each of which is specially adapted to perform a particular task, is attached to the tractor. Some implements are passive and are attached to a tractor to be pulled or pushed along by the tractor, as for example, a plow is pulled along in a plowing operation. Some implements are powered by the tractor, aside from being locomated by it, as for example, a mower is powered to rotate its cutting blades so that they strike across and cut grass blades.
A belt-driven implement gets its power from a tractor by means of a driven endless belt that is received around a pulley for a power take-off assembly, or PTO, of a tractor. The belt is also trained around a drive pulley that is part of the tractor's driving means. The pulley for the PTO takes off kinetic mechanical energy produced by the driving means of the tractor.
Because a tractor must carry out operations other than to power an implement--for instance, in a mowing operation a tractor must travel to a worksite and, at the worksite, must maneuver to turn around and avoid obstacles when not mowing--it is advantageous to have the PTO tap into the tractor's driving means while the driving means is operating. One structure that is advantageous in this regard has the belt loosely trained around both the drive pulley and the PTO pulley, so that while the drive pulley is operating, no power is taken off by the PTO pulley because there is no effective union between the pullies. Intermediate the two pulleys is an idler pulley that can be clutched into the belt to tighten the belt for a positive, linear relationship between the power supplied to the PTO pulley and the power supplied by the drive pulley. Thus, a clutching operation allows the PTO to effect a union with the driving means to receive power from the driving means; in like manner, the clutching operation breaks the union and thereby cuts off power to the PTO.
It is conventional to turn "on" and "off" the supply of power to an implement by a hand control conveniently situated near the operator of the tractor to which the implement is attached. Of the different types of hand controls, including rotating wheels, it is most convenient to use controls that are manipulated along a substantially straight line and, therefore, the shortest distance between "on" and "off" positions. Such controls are simple, quick, and efficient and tend to be the last tiring to tractor operators. It is to be appreciated that when the idler pulley is clutched into the belt by the control being manipulated to an "on" position, the belt exerts an opposite force resisting the idler pulley. This force is translated throughout the system that links the control to the clutching operation.
It is also to be appreciated that, when the idler pulley is clutched into a driven drive belt, it will be subjected to strong vibrations of a number of frequencies, particularly if the contact between the belt and the idler pulley is not true. This would place strain on the system causing undue wear and tear of the system's parts. It is also the caste that, when the contact is not true, the efficiency of the power tap is lost, causing unnecessary consumption of fuel and a loss of work output, as for example when there is skipping in the cutting operation of a mower implement.
It is this particular concern about the forces operating on the system, particularly when a true contact is not provided between an idler pulley of a PTO and a power-driven belt of a tractor, that focuses an important object of the present invention. The object is to provide an improved method of latching a linear control into an "off" or "on" position, thus keeping the vibrational frequencies to a minimum by keeping the contact between the component parts true and, thus, avoiding over-stressing the components of a PTO system. It follows that another object of the invention is to provide an improved linear control latch that utilizes the method.